Ionic and
Covalent Bonds
Notes
Essential Question:
What are Ions and
how are they
1formed?
2
What areIons?
 An
ion is an atom (or group of atoms)
that has a positive or negative charge
 Positive and negative ions are formed
when electrons are transferred (lost or
gained) between atoms
3
How do Metals form Ions?

Metals tend to LOSE electrons, from their outer
energy level



a positively charged particle is called cation
The charge is written as a number followed by a
plus sign: Na1+
Now named a “sodium ion”
4
How do nonmetals for ions?
 Nonmetals
electrons


tend to GAIN one or more
Negative ions are called anions
Cl1- is re-named a “chloride ion”
5
What are Polyatomic Ions?
 Group
of atoms that
act as a single unit that
have a charge
Example:
ammonium NH4+1
Carbonate CO3-2
6
What are valence electrons?
electrons in the outer energy
level, responsible for the chemical
properties of atoms.
The
7
How do you find valence e-?




The number of valence electrons are easily
determined. It is the group number for
elements in group 1A to 8A
Li group 1A has 1 valance electron
N group 5 A has 5 valance electrons
Exception He only has 2 valance electrons
8
Essential Questions
 Why
do atoms form bonds?
 What is the difference between how an
ionic bond forms and a covalent bond
forms?
9
What is the octet rule?
 When
forming compounds atoms want a
stable electron configuration like a noble
gas. This means 8 electrons in the outer
most shell.
10
How do atoms become stable?
 All
atoms react to try and achieve a noble gas
configuration.
 8 valence electrons = already stable!
 This is the octet rule (8 in the outer level is
particularly stable).
Ar
11
Electron Dots For Cations
Metals will lose the valence electrons
Ca
12
Electron Dots For Cations
 Forming
positive ions
2+
Ca
This is named the
“calcium ion”.
NO DOTS are now shown for the cation.
13
Electron Dots For Anions
 They
will gain electrons to fill outer shell.
P
3(This is called the “phosphide
ion”, and should show dots)
14
What are bonds?
Forces that hold groups of atoms together and
make them function as a unit.
What are the 3 types?
1)
2)
3)
Ionic bonds – transfer of electrons
Covalent bonds – sharing of
electrons.
Metallic bonds- “sea of electrons”
15
How do ionic bonds form?
 The
bond is formed through the transfer of electrons
(lose and gain)
 Anions and cations are held together by opposite
charges (+ and -)
 Usually a metal and nonmetal
 Ionic
compounds are called
 Electrons
salts.
are transferred to achieve noble gas
configuration.
16
What properties do Ionic compounds
have?
1.
2.
3.
4.
Crystalline solids - a regular repeating
arrangement of ions in the solid: Ions are
strongly bonded together.
Structure is rigid.
High melting points
Conduct electricity when dissolved in
water or melted (break apart into ions)
Brittle solids
17
Ionic Bonding
Na Cl
18
Ionic Bonding
+
Na
Cl
-
Note: Remember that NO DOTS
are now shown for the cation!
19
Ionic solids are brittle
Force
+
+
-
+
+
+
+
-
+
+
20
Ionic solids are brittle
 Strong
Repulsion breaks a crystal apart,
due to similar ions being next to each
other.
Force
- + - +
+ - + - + - +
21
- Page 198
The ions are free to move when they are
molten (or in aqueous solution), and thus
they are able to conduct the electric current.
22
How to read a formula
Ca3P2
Formula
Shows the kinds and numbers of atoms in
the substance.
23
How do covalent bonds form?
Always
two or more non-
metals
Electrons are shared to hold
two atoms together in a bond.
Form molecules
24
What are Diatomic Molecules?
A
molecule made of 2 atoms
 Memorize these 7 Br2, I2, N2,Cl2,
H2, O2, F2 “Dr. BrINClHOF”
25
What are the properties of molecular
compounds?

lower melting and boiling points than ionic
compounds
 tend
gases or liquids at room
to be
temperature
 Do
not break apart into ions when dissolved in
water stay in molecular form.
26
Covalent bonding
Fluorine
has seven valence electrons
(but would like to have 8)
F
27
Covalent bonding
Fluorine
has seven valence electrons
A second atom also has seven
F
F
28
Covalent bonding
F F
29
What are Metallic bonds?
How
metal atoms are held
together in the solid.
Metals hold on to their valence
electrons very weakly.
Think of them as positive ions
(cations) floating in a SEA OF
ELECTRONS
30
Sea of Electrons
+
+ + +
+ + + +
+ + + +
31
Due to the mobility of the
valence electrons, metals have:
1) Ductility and 2) Malleability
Notice
that the
ionic
crystal
breaks
due to ion
repulsion!